In the months following the 2012 Sandy Hook Elementary School shooting in Connecticut, where 20 small children were killed along with six adults, gun purchases rose—a common pattern as firearms enthusiasts afraid of new laws or interested in self-defense rush to stores. Gun manufacturer stock prices tend to rise, too.

“The spike in gun exposure that followed the Sandy Hook school shooting increased the incidence of accidental firearm deaths, particularly among children,” according to the study.

The research tracked increased “gun exposure” using the National Instant Criminal Background Check System. While the federal government doesn’t keep an exact tally of firearms sold, the system allows for an estimate because retailers are obligated to run such checks. Historically, gun sales in the U.S. have spiked after a mass shooting, though the trend has begun to taper off since President Donald Trump, a Republican and gun rights supporter, took office.

“Compared with other leading causes of death, gun violence was associated with less funding and fewer publications than predicted based on mortality rate”

The accidental deaths data used in the study was take from Vital Statistics kept by the Centers for Disease Control and Prevention, which has been constrained under federal law from pursuing similar research. The sales, they argue, serve as a “proxy” for what they call an increase in gun exposure among the public at large, though they concede they aren’t able to draw a causative link between the purchase of firearms following an attack and subsequent accidental deaths.

Gun sales “are correlated with an increased interest in firearms, even among current gun owners, as shown in our Google Trends analysis,” the researchers said. “We cannot determine the extent to which the impact is driven by sales or greater exposure to existing guns.”

While the study’s findings may seem fairly obvious, gun research in the U.S. is more difficult to come by because the federal government is effectively barred from funding it. “Compared with other leading causes of death, gun violence was associated with less funding and fewer publications than predicted based on mortality rate,” a January letter about research funding on gun violence published in the Journal of the American Medical Association stated.

Robin McKnight, a co-author of the study and economist at Wellesley University in Massachusetts, said she was inspired to research the topic after reading an article about rising gun sales after a mass shooting.

She and her co-author, Phillip B. Levine, “were interested in what the impact in having an extra 3 million firearms sales in a short period of time” would be. “We thought accidental firearm deaths was a likely place we might see some sort of effect. That’s what we found. The pattern we saw in the sales data was mirrored in the accidental deaths.”

In concluding their study, McKnight and Levine voiced their support for gun storage laws and counseling related to accidental firearms deaths. “I think it all highlights the importance of safe firearm storage,” McKnight said. “These accidents don’t happen when firearms are not easily accessible.”